The invention relates to improvements in devices for transmitting motion to flexible webs, for example, to webs of photosensitive material which must be transported through a developing machine. The invention also relates to a method of transporting webs with a conveyor, particularly with an endless belt conveyor.
Commonly owned U.S. Pat. No. 4,773,580 to Schweiger discloses a device which is used to transmit motion to elongated flexible webs and which can be used with advantage for attachment to a belt conveyor in order to transport webs of photographic paper or the like through successive liquid baths in a developing machine. The patented device has a frame-like first section which can be separably connected to a belt conveyor, and an elongated second section in the form of a flat arm having a longitudinally extending slot for the web which is to be entrained by the conveyor. The web is caused to pass through the slot so that the leader is located at one side and the next-following portion of the web is located at the other side of the slot. In the next step, the device is turned about an axis extending longitudinally of the slot so that the web is convoluted around the arm to thus ensure that the connection between the arm and the web will suffice to pull a relatively long web through the developing machine. The turning step entails that the leader is confined between the next-following portion of the web and the arm so that the web defines an elongated pocket which is open at its ends but is closed all the way along the slot. The pocket is filled with liquid when the web is caused to advance through the liquid baths in a developing machine. The last bath normally contains a supply of water for the purpose of rinsing successive increments of the advancing web before the web enters a drying chamber. The liquid which gathers in the pocket is not entirely evaporated in the drying chamber so that, when the device is thereupon detached from the conveyor, normally abruptly, droplets of water which remained in the pocket at the leading end of the web trickle along the web and remain on the web at the time the latter is convoluted onto a reel or spool. The droplets are caused to spread out between the convolutions of the web and form pools which bond the neighboring surfaces of convolutions to each other. When the web is removed from the reel, the bonds between abutting surfaces of neighboring convolutions are destroyed with attendant damage to the material of the web. If the liquid is permitted to penetrate all the way to the developed images on a web of photographic paper, the images are destroyed and the respective film frames must be copied again.